package com.shujia;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Mutation;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public class Demo7MRReadAndWriteHBase {
    public static class ReadHBase extends TableMapper<Text, IntWritable> {
        @Override
        protected void map(ImmutableBytesWritable key, Result value, Mapper<ImmutableBytesWritable, Result, Text, IntWritable>.Context context) throws IOException, InterruptedException {
            String rowkey = Bytes.toString(value.getRow());
            String clazz = Bytes.toString(value.getValue("info".getBytes(), "clazz".getBytes()));
            context.write(new Text(clazz), new IntWritable(1));
        }
    }

    public static class WriteHBase extends TableReducer<Text, IntWritable, NullWritable> {
        @Override
        protected void reduce(Text key, Iterable<IntWritable> values, Reducer<Text, IntWritable, NullWritable, Mutation>.Context context) throws IOException, InterruptedException {
            int cnt = 0;
            for (IntWritable value : values) {
                cnt++;
            }
            // create 'clazz_num','cf1'
            // KeyValue对象只能表示一个单元格cell
//            KeyValue keyValue = new KeyValue(key.getBytes(), "cf1".getBytes(), "cnt".getBytes(), (cnt + "").getBytes());
            // TableReducer需要reduce的输出的value为Mutation类型，只能使用Put对象
            Put put = new Put(key.getBytes());
            put.addColumn("cf1".getBytes(), "cnt".getBytes(), (cnt + "").getBytes());
            context.write(NullWritable.get(), put);
        }
    }

    public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {
        Configuration conf = new Configuration();
        conf.set("hbase.zookeeper.quorum", "master:2181,node1:2181,node2:2181");
        Job job = Job.getInstance(conf);
        job.setJobName("Demo7MRReadAndWriteHBase");
        job.setJarByClass(Demo7MRReadAndWriteHBase.class);

        // 使用TableMapReduceUtil配置Map任务
        TableMapReduceUtil.initTableMapperJob("students"
                , new Scan()
                , ReadHBase.class
                , Text.class
                , IntWritable.class
                , job
        );

        // 使用TableMapReduceUtil配置Reduce任务
        TableMapReduceUtil.initTableReducerJob("clazz_num"
                , WriteHBase.class
                , job);


        job.waitForCompletion(true);
    }
}
